Power Brake Booster
WARNING: This page is about a different car, the 2004 Ford Thunderbird. However, it is still accessible from the selected car via links, so may be relevant.
- Check hydraulic brake system for leaks or insufficient fluid. With transmission in Neutral, stop engine and apply parking brake control. Apply brake pedal several times to exhaust all vacuum in system.
- Apply brake pedal, and hold in this position. Start engine. If vacuum system is operating, pedal will tend to move downward under constant foot pressure. If no motion is felt, power brake booster system is not functioning. Go to next step.
- Remove hose from check valve connection. Manifold vacuum should be available at check valve (disconnected) end of hose. If manifold vacuum is available to power brake booster, connect vacuum booster hose onto check valve, and repeat steps 1 and 2 . If no downward movement of brake pedal is felt, install NEW power brake booster.
- Operate engine for minimum of 10 second at fast idle. Stop engine, and let vehicle stand for 10 minutes. Apply brake pedal with approximately 20 lbs. (9 kg) of force. Brake pedal feel should be same as noted when engine was operating. If pedal feels hard (no power assist), install new check valve, and retest. If pedal feels spongy, bleed system to remove air. See BLEEDING BRAKE SYSTEM .